[U-Boot] [PATCH] mmc: atmel: Properly fix clock configuration

[Gregory CLEMENT]

Timing issue occurs on eMMC not only when modifying the frequency but
also for all the switch command(CMD6). According to the MMC spec waiting
8 clocks after a switch command would be the thing to do.

This patch allows fixing CPU hang observed when trying to changing the
bus width on a eMMC on SAMA5D4.

Signed-off-by: Gregory CLEMENT <gregory.clement at free-electrons.com>
---
 drivers/mmc/gen_atmel_mci.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/gen_atmel_mci.c b/drivers/mmc/gen_atmel_mci.c
index da870c6..3f7cfba 100644
--- a/drivers/mmc/gen_atmel_mci.c
+++ b/drivers/mmc/gen_atmel_mci.c
@@ -36,6 +36,7 @@ struct atmel_mci_priv {
 	struct mmc_config	cfg;
 	struct atmel_mci	*mci;
 	unsigned int		initialized:1;
+	unsigned int		curr_clk;
 };
 
 /* Read Atmel MCI IP version */
@@ -91,7 +92,10 @@ static void mci_set_mode(struct mmc *mmc, u32 hz, u32 blklen)
 
 		}
 	}
-
+	if (version >= 0x500)
+		priv->curr_clk = bus_hz / (clkdiv * 2 + clkodd + 2);
+	else
+		priv->curr_clk = (bus_hz / (clkdiv + 1)) / 2;
 	blklen &= 0xfffc;
 
 	mr = MMCI_BF(CLKDIV, clkdiv);
@@ -118,8 +122,6 @@ static void mci_set_mode(struct mmc *mmc, u32 hz, u32 blklen)
 	if (mmc->card_caps & mmc->cfg->host_caps & MMC_MODE_HS)
 		writel(MMCI_BIT(HSMODE), &mci->cfg);
 
-	udelay(50);
-
 	priv->initialized = 1;
 }
 
@@ -284,8 +286,10 @@ mci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data)
 			{
 				u32 cnt = word_count * 4;
 				printf("Read Data:\n");
+				/*
 				print_buffer(0, data->dest + cnt * block_count,
 					     1, cnt, 0);
+				*/
 			}
 #endif
 #ifdef DEBUG
@@ -323,6 +327,12 @@ mci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data)
 		}
 	}
 
+	/* After the switch command, wait for 8 clocks before the next
+	 * command
+	 */
+	if (cmd->cmdidx == MMC_CMD_SWITCH)
+		udelay(8*1000000/ priv->curr_clk); /* 8 clk in us*/
+
 	return 0;
 }
 
-- 
2.5.0